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/model-pin-gate

PreToolUse model-pin guard for Fable seats: Agent/Task spawns must pin a non-Fable model; Workflow agent() pins are advisory. Triggers: model pin, Fable seat, Agent spawn, Workflow spawn.

$ golems-cli skills install model-pin-gate

Updated 1 week ago

Fleet law: canon #5 owns model policy. This skill is the Claude Code hook that enforces Fable-seat spawn pins.

What It Is

model-pin-gate is a Claude Code PreToolUse hook for Task|Agent|Workflow. It reads the current session's recent assistant model from transcript_path with a bounded tail read. If the current seat is not detectable as Fable, the hook allows the tool call. If the current seat is Fable, it enforces Etan's 2026-07-02 fleet model policy:

Tool call from a Fable seat	Verdict
`Agent` or `Task` without `tool_input.model`	BLOCK: `MODELPIN_AGENT_UNPINNED`
`Agent` or `Task` pinned to a Fable model	BLOCK: `MODELPIN_FABLE_BELOW_APEX`
`Agent` or `Task` pinned to a non-Fable model (`opus`, `sonnet`, `haiku`, or another explicit non-Fable model)	PASS
`Workflow` script with `agent(` calls and fewer `model:` pins than `agent(` calls	ADVISORY: `MODELPIN_WORKFLOW_AGENT_MODEL_ADVISORY`
`Workflow` script with enough `model:` pins	PASS
unrelated tools, malformed payloads, missing/undetectable seat model	PASS fail-open

The Workflow path is intentionally heuristic and advisory-only. It counts agent( occurrences versus model: occurrences and does not attempt full JavaScript parsing inside a 500ms hook.

Hook Contract

Input is the Claude Code PreToolUse stdin payload:

{
  "hook_event_name": "PreToolUse",
  "transcript_path": "/path/to/transcript.jsonl",
  "tool_name": "Agent",
  "tool_input": { "model": "opus", "prompt": "..." }
}

Output schema:

allow: {}
block: {"decision":"block","reason":"..."}
advisory: {"systemMessage":"..."}

The hook is local-only: no network, no BrainLayer, no subprocesses, bounded stdin/transcript reads, and fail-open on malformed input or internal errors.

install-snippet.json pins the absolute Node path: /Users/etanheyman/.nvm/versions/node/v22.22.0/bin/node.

Run It

bun test skills/golem-powers/model-pin-gate/evals/model-pin-gate.test.mjs
python3 skills/golem-powers/model-pin-gate/evals/run_suite.py

Programmatic: import { detectModelPin } from "./src/model-pin-gate.mjs" → detectModelPin(payload) returns { verdict, seatModel, tool, violations, advisories }.

Full SKILL.md source — includes LLM directives, anti-patterns, and technical instructions stripped from the Overview tab.